Plasmonic structures are widely used in modern biosensor design. various plasmonic resonant cavities could efficiently achieve a high Q-factor, improving the local field intensity to enhance photoluminescence or SERS (Surface-Enhanced Raman Scattering) of small molecules. Also, the combination between virus-like particles and plasmonic structures could significantly influence the scattering spectrum and field, which is utilized as a method for biological particle detection. In this paper, we designed one kind of gold plasmonic cavity with the shape of a split-ring. An edge gap and a bonus center bulge are introduced in the split-ring structure. Our simulation is based on Finite Difference Time Domain (FDTD) method. Polarization Indirect Microscopic Imaging (PIMI) technique is used here to detect far-field mode distribution under the resonant wavelength. The simulation results demonstrate resonant peaks in the visible spectrum at about 600 nm with a Q-factor reaches to 74. Localized hot spots are generated by an edge dipole mode and a cavity hexapole mode at resonant wavelength, which is according to dark points in the PIMI sinδ image. Also, the split-ring cavity shows a sensitivity when combined with biological particles. The scattering distribution is evidently changed as a result of energy exchange between particles and split-ring cavity, indicating a promising possibility for biosensing.
Human papillomavirus (HPV) remains a leading cause of virus-induced cancers. Hence early detection of HPV plays a crucial role in providing timely, optimal and effective intervention before such a cancer develops. While conventional light microscopy constitutes one of inseparable tools applied for studying biological cell structures, its low resolution at ~100nm per pixel falls short of detecting HPV that typically has a size of 52 to 55nm in diameter, giving rise to visualisation of HPV and subsequent evaluation of the efficacy of anti-HPV drugs at such sub-pixel level a challenging task if not overwhelmingly. This study employs an explainable deep learning network of texture transformer (TTSR) to up sample by four folds (×4). In comparison with other super resolution approaches, TTSR appears to perform the best with PSNR and SSIM being 28.70 and 0.8778 respectively whereas 25.80/0.7910, 18.35/0.5059. 30.31/0.8013, and 28.07/0.6074 are observed for the methods of RCAN, Pix2Pix, CycleGAN, and ESRGAN respectively. Significantly, the training pairs of TTSR does not need to be precisely match between low (LR) and high resolution (HR) images since the LR and HR images, which are required by many other super resolution approaches. This work constitutes one of the first to detect HPV applying explainable deep learning network, which will lead to the real world implementation to evaluate the efficacy of the developed anti-HPV drugs.
DNA nanoballs (DNBs) are the basis of combinatorial probe anchor ligation sequencing and the subject of multiple antisense oligonucleotides delivery research. To monitor and recognize the DNBs accurately in the procedure of genome sequencing or drug delivery is essential. Here, a super-resolution method called parametric indirect microscopic imaging (PIMI) is applied to image the DNBs. By generating the necessary polarization azimuth, phase variation, and Stokes parameters through polarization modulation, the variation of point fields in a sample can be precisely recorded and used to describe how light coupling and scattering are different from point to point. Based on the Jones paraxial propagation model and the goodness of fit to the variation curve, the image resolution is no longer limited by optical diffraction after filtering off the scattering from all uncorrelated surrounding objective field points. Results show that PIMI can reveal the spatial distribution and morphology of DNBs, break the diffraction limit, and bring the resolution within 150 nm. We proved the advantages of PIMI for its super-resolving power of DNBs in a label-free, wide-field imaging manner, which opens opportunities for developing low cost, high throughput imaging tools for DNB metrology applications.
Detailed imaging and analysis of skin structures are becoming increasingly important in modern healthcare and clinic diagnosis. Nanometer resolution imaging techniques such as SEM and AFM can cause harmful damage to the sample and cannot measure the whole skin structure from the very surface through epidermis, dermis to subcutaneous. Conventional optical microscopy has the highest imaging efficiency, flexibility in onsite applications and lowest cost in manufacturing and usage, but its image resolution is too low to be accepted for biomedical analysis. Infrared parameter indirect microscopic imaging (PIMI) uses an infrared laser as the light source due to its high transmission in skins. The polarization of optical wave through the skin sample was modulated while the variation of the optical field was observed at the imaging plane. The intensity variation curve of each pixel was fitted to extract the near field polarization parameters to form indirect images. During the through-skin light modulation and image retrieving process, the curve fitting removes the blurring scattering from neighboring pixels and keeps only the field variations related to local skin structures. By using the infrared PIMI, we can break the diffraction limit, bring the wide field optical image resolution to sub-200nm, in the meantime of taking advantage of high transmission of infrared waves in skin structures.
KEYWORDS: Polarization, Near field, Point spread functions, Near field optics, Imaging systems, Modulation, Structured optical fibers, Anisotropy, Scattering, Tissues
Social order is threatened by counterfeit money. Conventional anti-counterfeit technology is much too old to identify its authenticity or not. The intrinsic difference between genuine notes and counterfeit notes is its paper tissue. In this paper a new technology of detecting RMB is introduced, the polarization parameter indirect microscopic imaging technique. A conventional reflection microscopic system is used as the basic optical system, and inserting into it with polarization-modulation mechanics. The near-field structural characteristics can be delivered by optical wave and material coupling. According to coupling and conduction physics, calculate the changes of optical wave parameters, then get the curves of the intensity of the image. By analyzing near-field polarization parameters in nanoscale, finally calculate indirect polarization parameter imaging of the fiber of the paper tissue in order to identify its authenticity.
KEYWORDS: Polarization, Imaging systems, Diffraction, Near field optics, Near field, Graphene, Point spread functions, Image resolution, Modulation, Super resolution
The resolution of conventional optical microscope is intrinsically limited by the optical diffraction, therefore it cannot be used in the measurement of sub-100nm shape and structural detection. Non-optical imaging techniques are not limited by the optical diffraction. For example, scanning tunneling microscopy (STM) and atomic force microscopy (AFM), but both of them have the weakness of narrow view field, low efficiency, and excessive cost. To detect nanoscale material, a new microscopic imaging technique is introduced in this paper, i.e. the polarization parameter indirect microscopic imaging technique. A conventional reflection microscopic system is used as the basic optical system, with polarization-modulation mechanics being inserted into it. The near-field structural characteristics can be delivered by optical wave and material coupling. According to coupling and conduction physics, changes of the optical wave parameters can be calculated, and then curves of the image intensity can be obtained. By analyzing the near-field polarization parameters in nanoscale, indirect polarization parameter imaging can be established.
We report a new method, polarization parameters indirect microscopic imaging with a high transmission infrared light source, to detect the morphology and component of human skin. A conventional reflection microscopic system is used as the basic optical system, into which a polarization-modulation mechanics is inserted and a high transmission infrared light source is utilized. The near-field structural characteristics of human skin can be delivered by infrared waves and material coupling. According to coupling and conduction physics, changes of the optical wave parameters can be calculated and curves of the intensity of the image can be obtained. By analyzing the near-field polarization parameters in nanoscale, we can finally get the inversion images of human skin. Compared with the conventional direct optical microscope, this method can break diffraction limit and achieve a super resolution of sub-100nm. Besides, the method is more sensitive to the edges, wrinkles, boundaries and impurity particles.
Simple polarization indirect microscopic imaging can visualize graphene layer's dimensions features, however, its limited resolution makes it impossible to analyze the other physical characteristics. Our research uses polarization parameter indirect microscopic imaging system with super-resolution to modulate the variation of far field point spread function with varying polarization status and improve wavefront aberration, sensor error, and polarization angle. This method has much higher sensitivity to graphene overlapping layers, edges, wrinkles and grain boundaries. Finally, this technique for graphene inspection that is capable of reaching super-resolution.
With the development of modern precision optical systems, optical detecting system requires the accuracy of wavefront aberration to arrive to sub-nanometer level. When the incident field with polarization information, the polarization information will have a significant impact on the accuracy of measurement results by interacting with polarization-sensitive optical components in the lateral shearing interferometer. We propose the integrated interferometer wavefront sensor (IIWS) system, which is based on the traditional lateral shearing interferometer. This wavefront is sheared by a two-dimension diffraction grating in our system, the two-dimension diffraction grating is the key element to analysis the metrology performance. When using a different grating period and shearing direction, the wavefront shearing and phase shifting with polarization information will produce different error, moreover the impact will vary in the different diffraction orders. In this paper, calculation is based on the finite difference time domain (FDTD) algorithm. When calculation of different polarization state distribution of the incident field, the interaction analysis of shearing phase shifted grating and incidence light play an important role in error analysis. Finally we can get the effect of polarization for grating performance.
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